STOCKHOLM (AP) ' U.N. climate chief Christiana Figueres says she will leave her post in July after six years in charge of the diplomatic effort to fight global warming.The Costa Rican diplomat's announcement Friday comes two months after a historic international agreement on climate change was adopted in Paris.In a letter to governments and observers of the talks, the 59-year-old Figueres said she would "not accept an extension" when her term ends in July.Figueres helped rescue the climate talks after a tumultuous 2009 summit in Copenhagen and put them on a path that culminated with the Paris Agreement, the first deal asking all countries to rein in their greenhouse gas emissions."The Paris Agreement is a historical achievement, built on years of increasing willingness to construct bridges of collaboration and solidarity," she wrote in the letter. "It has been an honor to support you along this path over the past six years."Figueres said U.N. Secretary-General Ban Ki-moon "will soon initiate the search" for her successor.Alden Meyer of the Union of Concerned Scientists, a veteran observer of the climate talks, said Figueres would leave on a high note."She was an essential part of the success in Paris," he said. "She had the knowledge of the issues, the understanding of the politics and the willingness to engage with non-state actors and use them to build momentum."Set to take effect in 2020, the Paris Agreement requires all countries to submit plans for climate action and to update them at regular intervals. The plans themselves are not legally binding.The U.N.'s expert panel on climate science says soaring emissions of greenhouse gases, primarily from the burning of fossil fuels, are the main reason for the rise in global temperatures since the middle of the 20th century.Also Friday, the executive director of the Green Climate Fund, Hela Cheikhrouhou, said she will step down when her three-year term ends in September. The fund is one of the main channels of climate finance to help poor countries reduce their emissions and adapt to rising sea levels, droughts, floods and other impacts of climate change.Join the conversation about this story Click here to read full news..